This invention relates to a control device for maintaining the pressure in a cylinder at a desired value.
In a general purpose industrial robot, the robot hand is moved vertically by a vertical feed screw and a motor for driving the feed screw. In this case, the light weight of the robot hand or the like is applied as a load on the motor at all times. The motor load can be reduced by holding the light weight of the robot hand with the force of the pressurized cylinder.
However, the motor load is affected not only by the inherent weight of the robot hand or the like, but also by the weight of an object gripped by the robot hand, the inertia of the robot hand in motion and external forces applied to the robot hand during acceleration or deceleration which represent variable loads applied to the motor. Therefore, the pressure in the cylinder must be controlled with high accuracy while tracking the motor load at all times. This cannot be achieved by a conventional pressure control device.